A flat intermediate element may be provided on a fuel injector installed in a receiving bore in a cylinder head of an internal combustion engine. Such intermediate elements as supporting elements in the form of a washer are placed on a shoulder of the receiving bore of the cylinder head in a conventional way. With the help of such intermediate elements, manufacturing tolerances and assembly tolerances are compensated and a bearing support free of transverse forces is ensured even when the fuel injector is in a slightly skewed position. The fuel injection device is suitable for use in fuel injection systems in mixture-compressing, spark-ignition internal combustion engines in particular.
Another type of simple intermediate element for a fuel injection device is described in German Patent No. DE 101 08 466 A1. This intermediate element is a washer having a circular cross section and is situated an area where both the fuel injector and the wall of the receiving bore have a truncated conical shape in the cylinder head, and the washer acts as an equalizing element for bearing and support of the fuel injector.
More complex intermediate elements for fuel injection devices, which are more complicated to manufacture, are described in German Patent Application Nos. DE 100 27 662 A1, and DE 100 38 763 A1 and European Patent No. EP 1 223 337 A1, among others. These intermediate elements are characterized in that they are all constructed in multiple layers or multiple parts and should undertake sealing and damping functions to some extent. The intermediate element described in German Patent Application No. DE 100 27 662 A1 has a base body and a carrier body, in which a sealant through which a nozzle body of the fuel injector passes is used. German Patent Application No. DE 100 38 763 A1 describes a multilayer equalizing element made up of two rigid rings and an elastic intermediate ring sandwiched in between. This equalizing element permits tilting of the fuel injector relative to the axis of the receiving bore over a relatively large angle range as well as radial displacement of the fuel injector from the central axis of the receiving bore.
European Patent No. EP 1 223 337 A1 also describes a multilayer intermediate element composed of multiple washers, each made of a damping material. The damping material made of metal, rubber or PTFE is selected and designed in such a way that it enables damping of the vibrations and noises generated by operation of the fuel injector. However, the intermediate element must have four to six layers to achieve the desired damping effect.
To reduce noise emissions, U.S. Pat. No. 6,009,856 A also proposes to surround the fuel injector using a sleeve and to fill the created gap with an elastic noise-absorbing material. However, this type of noise damping is very complex, difficult to install and expensive.